1. Field of Invention
The present invention relates to a semiconductor light emitting device grown on a wavelength converting composite substrate.
2. Description of Related Art
Semiconductor light-emitting devices including light emitting diodes (LEDs), resonant cavity light emitting diodes (RCLEDs), vertical cavity laser diodes (VCSELs), and edge emitting lasers are among the most efficient light sources currently available. Materials systems currently of interest in the manufacture of high-brightness light emitting devices capable of operation across the visible spectrum include Group III-V semiconductors, particularly binary, ternary, and quaternary alloys of gallium, aluminum, indium, and nitrogen, also referred to as III-nitride materials. Typically, III-nitride light emitting devices are fabricated by epitaxially growing a stack of semiconductor layers of different compositions and dopant concentrations on a sapphire, silicon carbide, III-nitride, or other suitable substrate by metal-organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), or other epitaxial techniques. The stack often includes one or more n-type layers doped with, for example, Si, formed over the substrate, one or more light emitting layers in an active region formed over the n-type layer or layers, and one or more p-type layers doped with, for example, Mg, formed over the active region. Electrical contacts are formed on the n- and p-type regions.
FIG. 1 illustrates an LED described in more detail in U.S. Pat. No. 7,514,721, which is incorporated herein by reference. “A luminescent ceramic 52 is bonded to a nucleation structure 58 by a bond 56 at the interface between the nucleation structure 58 and the luminescent ceramic, either directly by wafer bonding or through an intermediate bonding layer (not shown). If a bonding layer is used, the bonding layer preferably has an index of refraction between the indices of refraction of the III-nitride layer to which the bonding layer is applied and the luminescent ceramic, though bonding layers with lower indices of refraction may be used. Epitaxial layers including a light emitting region 14 disposed between an n-type region 10 and a p-type region 12 are then grown on the nucleation structure.” N- and p-contacts 18 and 20 are formed on the n- and p-type regions 10 and 12.